How do neurons conduct nerve impulses?

1. How do neurons conduct nerve impulses? • Neurons conduct nerve impulses through an electrochemical signal called an • An action potential is generated by the • Ions are • Membranes of neurons contain ion channels, which allow passage of ions between the

2. Neuron at Rest (before impulse) • At rest, the inside of the neuron is • The membrane is described as

3. Neuron Depolarization (During a Nerve Impulse) • Stimulation of the neuron, • The inside of the neuron is now • This is called • The adjacent section of membrane allows

4. Nerve Repolarization(After a Nerve Impulse) • After a short time, • K+ ions continue to exit the neuron, thus • Known as animation

5. Refractory Period • After an action potential occurs, there is a short time during which the • As a result, Animation - http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter44/action_potential_propagation_in_an_unmyelinated_axon.html

6. All-or Nothing Action Potenitals • Action potentials are • The action potential only occurs if the stimulus causes enough sodium ions to enter the cell thus • If too few Na+ ions enter the cell,

7. How fast are nerve impulses? • Action potentials can travel along axons at speeds of • Thus, nerve impulses can get from one part of a body to another in

8. Review of Nerve Impulse – Place the following events in order • The neuron is repolarized • A stimulus reaches the neuron • The neuron enters a refractory period • Na+ channels open allowing Na+ to flood into the neuron • The neuron is depolarized • Na+ channels close while K+ channels open allowing K+ to flow out of the neuron

9. Transmitting the Impulse Across a Synapse • The end of a neuron where • When the impulse reaches a synapse, it must be transferred to the next neuron. • Problem: • Solution:

10. Label the Structures of a Synapse • a. • b. • c. • d. • e.

11. Neurotransmission Process

12. Neurotransmission Process (Cont) http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter8/animation__transmission_across_a_synapse.html

13. Useful Animations • http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter8/animation__the_nerve_impulse.html • http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter8/animation__transmission_across_a_synapse.html